linux-kernel - [RFT PATCH v2 11/12] drm/radeon: Call drm_helper_force_disable

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Date:   Thu, 21 Sep 2023 12:26:54 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     dri-devel@...ts.freedesktop.org, Maxime Ripard <mripard@...nel.org>
Cc:     Douglas Anderson <dianders@...omium.org>, Xinhui.Pan@....com,
        airlied@...il.com, alexander.deucher@....com,
        amd-gfx@...ts.freedesktop.org, christian.koenig@....com,
        daniel@...ll.ch, linux-kernel@...r.kernel.org
Subject: [RFT PATCH v2 11/12] drm/radeon: Call drm_helper_force_disable_all() at shutdown/remove time

Based on grepping through the source code, this driver appears to be
missing a call to drm_atomic_helper_shutdown(), or in this case the
non-atomic equivalent drm_helper_force_disable_all(), at system
shutdown time and at driver remove time. This is important because
drm_helper_force_disable_all() will cause panels to get disabled
cleanly which may be important for their power sequencing. Future
changes will remove any custom powering off in individual panel
drivers so the DRM drivers need to start getting this right.

The fact that we should call drm_atomic_helper_shutdown(), or in this
case the non-atomic equivalent drm_helper_force_disable_all(), in the
case of OS shutdown/restart comes straight out of the kernel doc
"driver instance overview" in drm_drv.c.

NOTE: in order to get things inserted in the right place, I had to
replace the old/deprecated drm_put_dev() function with the equivalent
new calls.

Suggested-by: Maxime Ripard <mripard@...nel.org>
Reviewed-by: Maxime Ripard <mripard@...nel.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
I honestly have no idea if I got this patch right. The shutdown()
function already had some special case logic for PPC, Loongson, and
VMs and I don't 100% for sure know how this interacts with
those. Everything here is just compile tested.

(no changes since v1)

 drivers/gpu/drm/radeon/radeon_drv.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 39cdede460b5..67995ea24852 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -38,6 +38,7 @@
 #include <linux/pci.h>

 #include <drm/drm_aperture.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
 #include <drm/drm_gem.h>
@@ -357,7 +358,9 @@ radeon_pci_remove(struct pci_dev *pdev)
 {
 	struct drm_device *dev = pci_get_drvdata(pdev);

-	drm_put_dev(dev);
+	drm_dev_unregister(dev);
+	drm_helper_force_disable_all(dev);
+	drm_dev_put(dev);
 }

 static void
@@ -368,6 +371,8 @@ radeon_pci_shutdown(struct pci_dev *pdev)
 	 */
 	if (radeon_device_is_virtual())
 		radeon_pci_remove(pdev);
+	else
+		drm_helper_force_disable_all(pci_get_drvdata(pdev));

 #if defined(CONFIG_PPC64) || defined(CONFIG_MACH_LOONGSON64)
 	/*
-- 
2.42.0.515.g380fc7ccd1-goog